The present invention relates to ophthalmic lenses adapted for direct contact with eye tissue, and more particularly to procedures for forming identifying symbols upon such lenses.
It has long been known that the vision of the human eye can be aided by disposing a small, transparent lens directly upon the surface of the eye, the contours of the lens supplementing and correcting the effect of the biological lens within the eyeball. In recent years the materials and techniques for manufacturing such lenses have improved markedly, with the result that contact lenses are being worn in ever-increasing numbers. Certain recent advances in contact lens technology, particularly the introduction of the so-called "soft" contact lens, has led to still further popularity of contact lenses. Unlike the well-known "hard" contact lens, the soft lens is relatively pliable, particularly when it is in use and hydrated.
Certain problems inhere in the use of contact lenses. Of particular interest is the difficulty in uniquely identifying lenses. With the aid of specialized intrumentation the optical qualities of a given contact lens may be measured, and thus in some respects a lens may be identified. However, in the broad sense it is difficult to uniquely identify lenses inasmuch as they are relatively small and look substantially alike even under mangification.
The ability to identify individual lenses, though it would be extremely useful to lens wearers and to ophthalmologists and opticians, has so far eluded the industry. It would, for instance, be extremely useful for a wearer to be able to differentiate between lenses for left and right eyes. Still further, it would be essential to identify lenses in the event they are accidentally commingled. This could occur at various stages during their manufacture, shipment or preparation in the office of a fitter. In addition, it would in many cases be extremely useful to be able to identify the manufacturer, material lot, and production run of a given lens; and finally to be able to identify the optical characteristics of a lens without actually measuring them.
A number of solutions have been suggested, and in some cases experimented with. For instance, identifying characters could be imprinted upon the surface of the lens. This approach, however, requires the application of a separate material to the lens with the accompanying danger of its separation therefrom. Further, inasmuch as some contact lenses are subject to rigid governmental requirements, the addition of extraneous materials would require lengthy testing and qualification procedures.
It has further been suggested that identifying indicia be machined or mechanically etched into the surface of a contact lens. While this approach has been tried, it has met with little success due to the difficulty of physically machining or scratching marks into the surface of the lens with conventional apparatus. The difficulty in actually machining the surface of the lens with miniscule tools is apparent, although some efforts have been made to scratch symbols into a lens surface using a pantograph.
For all of the foregoing reasons, it will be appreciated that there is a need for an improved method for applying identifying indicia to contact lenses, which does not require the addition of extraneous material to the lens itself and which is economically feasible.
It is therefore an object of the present invention to provide a method of applying identifying indicia to contact lenses.
Another object is to provide an improved method for etching symbols into the surface of an ophthalmic contact lens.
A further object is to provide a system for reliably and uniquely applying identifying indicia to sequentially-presented contact lenses.
Yet another object is to provide a contact lens having identifying indicia formed by the impingement of a high-energy beam of light that interacts with the lens material.